The present invention relates to manufacturing methods of semiconductor devices, and more particularly, to a manufacturing method of a semiconductor device including a metal oxide semiconductor (MOS) transistor.
In recent years, metal oxide semiconductor (MOS) transistors have been required to have an improved current drive capability so as to achieve higher performance of an electronic device and reduction in consumed power of the device. In order to enhance the current drive capability, gate electrodes have been developed which include an insulating film having a higher dielectric constant (High-k film) than that of a SiO2 film or a SiON film as a gate insulating film, and a metal film made of metal material having a predetermined work function as a gate electrode portion. Typically, a hafnium-based oxide film, such as a HfO2 film, a HfON film, or a HfSiON film, is applied as the High-k film, and titanium nitride (TiN) or the like is applied as the metal material.
In source/drain regions of the MOS transistor, extension regions are formed to overlap the gate electrode in shallow junction. The extension region is formed in the following way. First, a polysilicon film, a metal film, and a High-k film, which are to serve as a gate electrode of the MOS transistor, are patterned. Then, an offset spacer having a predetermined thickness is formed on each side of the metal film and High-k film patterned or the like. Thereafter, the extension region is formed by implanting impurity ions of a predetermined conductive type using the offset spacer as a mask.
Conventionally, in the gate electrode formed using the High-k film and the metal film, a silicon nitride (SiN) film is applied as the offset spacer. The silicon nitride film, however, has a relatively high dielectric constant, and thus has limited the improvement of an operation speed of the MOS transistor. Thus, in order to further improve the operation speed of the MOS transistor, the application of a silicon oxide film having a lower dielectric constant has been promoted. For example, Patent Documents 1 and 2 disclose a semiconductor device having an offset spacer formed on each side of a gate electrode made of a High-k film and a metal film.
[Related Art Documents]
[Patent Documents]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-114522
[Non-Patent Document 2]
Japanese Unexamined Patent Publication No. 2008-60538